When electronic products are becoming smaller in size and more intelligent with a high performance and a high reliability, requirements to integrated circuit (IC) fabrication techniques are accordingly increased for higher integration of IC. Among these IC fabrication techniques, photolithography process is an important technique used in forming selected circuit patterns on a substrate wafer. In general, a photoresist film can be deposited onto the substrate wafer during this process and thereafter pattern-exposed to lithographic equipment in order to transcribe a selected circuit pattern. The photoresist film is subsequently developed with a developer solution to obtain a resist pattern corresponding to the transcribed pattern. The developer solution is intended to remove the relatively more soluble areas of photoresist, and leave behind the remaining patterned image which basically serves as a mask for etching multiple thin film layers on the substrate wafer.
In order to form desired patterns of multiple thin film layers the on the substrate wafer, light-exposed photoresist film is then processed in a developing process with the developer solution and a rinse solution for washing out excess developer solution. For example, the developer solution is dispensed onto the substrate wafer. A developer solution film may be thus formed which is intended to have a relatively uniform thickness across the surface of the substrate wafer. The developer film is formed thereon so that the developer solution contacts with the resist-coated wafer in order to develop a light-exposed latent image. Upon completion of this step in the development process, the rinse solution can be supplied onto the surface of the wafer. By rotating the wafer at a relatively high speed, the rinse solution may be eventually scattered off to spin dry the surface of the wafer and complete the developing process. The developing process plays a very important role on forming desired patterns of multiple thin film layers the on the substrate wafer.
As aforementioned, since requirements to IC fabrication techniques are increased for higher integration of IC, precise formation of desired patterns of multiple thin film layers the on the substrate wafer is accordingly becoming challenging and difficult. Accordingly, improvements in tools and methods of the developing process continue to be sought.